Flexible display device

ABSTRACT

A flexible display device includes: a display panel capable of being bent with respect to a folding line; and a metal plate disposed on the display panel and capable of being bent with respect to the folding line. The metal plate has a plurality of holes disposed on each side of the folding line, the plurality of holes being formed in a zigzag pattern with respect to the folding line.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119 to Korean PatentApplication No. 10-2016-0132166, filed on Oct. 12, 2016, in the KoreanIntellectual Property Office (KIPO), the disclosure of which isincorporated by reference herein in its entirety.

TECHNICAL FIELD

Exemplary embodiments of the present inventive concept relate to aflexible display device, and more particularly, to a flexible displaydevice capable of distributing stress at a bending portion.

DISCUSSION OF RELATED ART

In recent times, flexible display devices that may be bent are beingdeveloped. Such a flexible display device may be used in various fieldssince it may be folded or bent in various shapes. In the flexibledisplay device, a display element is disposed on a flexible substrate.

Display elements applicable to flexible display devices may includeorganic light emitting diodes (“OLED”), liquid crystal display (“LCD”)elements, and electrophoretic display (“EPD”) elements. Among these,OLED may be manufactured in a thin film-like laminated structure, andthus has excellent flexibility and is garnering attention as displayelements of flexible display devices.

Flexible display devices may be classified into rollable display devicesthat may be rolled as a scroll, foldable display devices that may befolded as paper, and stretchable display devices that may be scaled upand down, depending on the degree of being bent.

The flexible display device may include a metal plate or a metal sheetfor dissipating heat and shielding electromagnetic waves, and in such acase, a flexible metal plate or a flexible metal sheet may be used.However, in the case of using a flexible metal plate or a flexible metalsheet, a bending portion of the metal plate may be deformed due torepeated bending actions.

It is to be understood that this background of the technology section isintended to provide useful background for understanding the technologyand as such disclosed herein, the technology background section mayinclude ideas, concepts or recognitions that were not part of what wasknown or appreciated by those skilled in the pertinent art prior to acorresponding effective filing date of subject matter disclosed herein.

SUMMARY

Exemplary embodiments of the present inventive concept may be directedto a flexible display device in which a metal plate or a metal sheet fordissipating heat and shielding electromagnetic waves are not deformedalthough a flexible display panel is bent.

According to an exemplary embodiment, a flexible display deviceincludes: a display panel capable of being bent with respect to afolding line; and a metal plate disposed on the display panel andcapable of being bent with respect to the folding line. The metal platehas a plurality of holes disposed on each side of the folding line, theplurality of holes being formed in a zigzag pattern with respect to thefolding line.

Each of the plurality of holes may have an elliptical shape in a planview.

The elliptical shape may have a major axis parallel to the folding line.

The metal plate may include: a bending portion bent with respect to thefolding line; and a planar portion extending from the bending portion.

The each of the plurality of holes may be formed at a boundary betweenthe bending portion and the planar portion.

The plurality of holes may be spaced apart from the folding line.

The plurality of holes may be spaced apart from the folding line by adistance greater than or equal to about 0.1 mm and less than or equal toabout 10 mm.

The plurality of holes may include at least one group of holes disposedon one side of the folding line, each group of holes including apredetermined number of holes.

The groups of holes may be formed in a zigzag pattern with respect to animaginary line parallel to the folding line.

The metal plate may include a high modulus material.

The metal plate may include at least one selected from the groupconsisting of: copper (Cu), invar, nobinite, stainless steel, and alloysthereof.

The metal plate may have a substantially same shape as a shape of thedisplay panel in a plan view.

The flexible display device may further include a light blocking layerdisposed between the display panel and the metal plate.

The flexible display device may further include a cushion layer disposedbetween the display panel and the metal plate.

According to another exemplary embodiment, a flexible display deviceincludes: a metal plate capable of being bent with respect to a foldingline, a display panel disposed on the metal plate and capable of beingbent with respect to the folding line; and a touch sensor disposed onthe display panel. The metal plate has a plurality of holes disposed oneach side of the folding line, the plurality of holes being formed in azigzag pattern with respect to the folding line.

The flexible display device may further include a polarizer disposed onthe display panel.

Each of the plurality of holes may have an elliptical shape in a planview.

The elliptical shape may have a major axis parallel to the folding line.

The plurality of holes may include at least one group of holes disposedon one side of the folding line, each group of holes including apredetermined number of holes.

The groups of holes may be formed in a zigzag pattern with respect to animaginary line parallel to the folding line.

The foregoing is illustrative only and is not intended to be in any waylimiting. In addition to the illustrative aspects, exemplaryembodiments, and features described above, further aspects, exemplaryembodiments, and features will become apparent by reference to thedrawings and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the present inventive concept willbecome more apparent by describing in detail exemplary embodimentsthereof with reference to the accompanying drawings, wherein:

FIG. 1 is an exploded perspective view illustrating an exemplaryembodiment of a flexible display device;

FIG. 2 is a perspective view illustrating an exemplary embodiment of theflexible display device in a folded state;

FIG. 3 is a perspective view illustrating a metal plate according to anexemplary embodiment;

FIG. 4 is a partial enlarged view illustrating area “A” of FIG. 3;

FIG. 5 is a cross-sectional view illustrating an exemplary embodiment ofthe flexible display device in a folded state;

FIGS. 6 and 7 are plan views illustrating a portion of a metal plateaccording to an alternative exemplary embodiment;

FIG. 8 is a partial enlarged view illustrating a portion of a displaypanel according to an exemplary embodiment; and

FIG. 9 is a cross-sectional view taken along line I-I′ of FIG. 8.

DETAILED DESCRIPTION

Exemplary embodiments will now be described more fully hereinafter withreference to the accompanying drawings. Although the inventive conceptmay be modified in various manners and have several exemplaryembodiments, exemplary embodiments are illustrated in the accompanyingdrawings and will be mainly described in the specification. However, thescope of the inventive concept is not limited to the exemplaryembodiments and should be construed as including all the changes,equivalents, and substitutions included in the spirit and scope of theinventive concept.

In the drawings, thicknesses of a plurality of layers and areas areillustrated in an enlarged manner for clarity and ease of descriptionthereof. When a layer, area, or plate is referred to as being “on”another layer, area, or plate, it may be directly on the other layer,area, or plate, or intervening layers, areas, or plates may be presenttherebetween. Conversely, when a layer, area, or plate is referred to asbeing “directly on” another layer, area, or plate, intervening layers,areas, or plates may be absent therebetween. Further when a layer, area,or plate is referred to as being “below” another layer, area, or plate,it may be directly below the other layer, area, or plate, or interveninglayers, areas, or plates may be present therebetween. Conversely, when alayer, area, or plate is referred to as being “directly below” anotherlayer, area, or plate, intervening layers, areas, or plates may beabsent therebetween.

The spatially relative terms “below”, “beneath”, “less”, “above”,“upper”, and the like, may be used herein for ease of description todescribe the relations between one element or component and anotherelement or component as illustrated in the drawings. It will beunderstood that the spatially relative terms are intended to encompassdifferent orientations of the device in use or operation, in addition tothe orientation depicted in the drawings. For example, in the case wherea device illustrated in the drawing is turned over, the devicepositioned “below” or “beneath” another device may be placed “above”another device. Accordingly, the illustrative term “below” may includeboth the lower and upper positions. The device may also be oriented inthe other direction, and thus the spatially relative terms may beinterpreted differently depending on the orientations.

Throughout the specification, when an element is referred to as being“connected” to another element, the element is “directly connected” tothe other element, or “electrically connected” to the other element withone or more intervening elements interposed therebetween. It will befurther understood that the terms “comprises,” “comprising,” “includes”and/or “including,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

It will be understood that, although the terms “first,” “second,”“third,” and the like may be used herein to describe various elements,these elements should not be limited by these terms. These terms areonly used to distinguish one element from another element. Thus, “afirst element” discussed below could be termed “a second element” or “athird element,” and “a second element” and “a third element” can betermed likewise without departing from the teachings herein.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

Unless otherwise defined, all terms used herein (including technical andscientific terms) have the same meaning as commonly understood by thoseskilled in the art to which this inventive concept pertains. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an ideal or excessively formal sense unlessclearly defined in the present specification.

Some of the parts which are not associated with the description may notbe provided in order to specifically describe exemplary embodiments ofthe present inventive concept, and like reference numerals refer to likeelements throughout the specification.

FIG. 1 is an exploded perspective view illustrating an exemplaryembodiment of a flexible display device, and FIG. 2 is a perspectiveview illustrating an exemplary embodiment of the flexible display devicein a folded state.

Referring to FIGS. 1 and 2, a flexible display device according to anexemplary embodiment includes a display panel 100, a light blockinglayer 300 disposed on the display panel 100, a cushion layer 400disposed on the light blocking layer 300, and a metal plate 500 disposedon the cushion layer 400.

However, exemplary embodiments are not limited thereto, and the flexibledisplay device may further include a cover glass (not illustrated)disposed on the display panel 100 to face the light blocking layer 300with the display panel 100 interposed therebetween. The cover glassincludes a transparent rigid material, and thus may protect the displaypanel 100 from external impact while allowing an image of the displaypanel 100 to pass therethrough.

A touch sensor (not illustrated) may be disposed between the displaypanel 100 and the cover glass to detect a user's touch action. The touchsensor may be provided on a separate substrate to be disposed on thedisplay panel 100 or may be implemented directly in the display panel100.

In addition, a polarizer (not illustrated) may be disposed between thedisplay panel 100 and the cover glass. The polarizer may be disposed onthe display panel 100 to prevent reflection of external light.

The display panel 100 according to an exemplary embodiment may be aflexible display panel that may be bent with respect to a folding lineFL.

The display panel 100 according to an exemplary embodiment may include abending portion 101 that may be bent with respect to the folding line FLand planar portions 102 on opposite sides of the bending portion 101.

In the drawings, the display panel 100 is depicted as being bent inbilateral symmetry with respect to the folding line FL. However,exemplary embodiments are not limited thereto, and the display panel 100may be bent in bilateral asymmetry.

Although described separately for ease of description, the bendingportion 101 and the planar portion 102 of the display panel 100 may besubstantially one display area. The plurality of pixels are disposed ineach of the bending portion 101 and the planar portion 102 of thedisplay panel 100 to display an image.

In addition, the display panel 100 according to an exemplary embodimentis described on the assumption that the display panel 100 is bentinwardly with respect to an area on which an image is displayed, butexemplary embodiments are not limited thereto. In one embodiment, thedisplay panel 100 may be bent outwardly with respect to the area onwhich an image is displayed.

The display panel 100 may include, for example, a flexible film such asa plastic film, and may be implemented by forming an organic lightemitting diode (“OLED”) and a pixel circuit on the flexible film. A moredetailed configuration of the display panel 100 will be described below.

The light blocking layer 300 may be disposed on a rear surface of thedisplay panel 100. The light blocking layer 300 may block areas of thedisplay panel 100, except an area where an image is output, from beingvisible to users. For example, the light blocking layer 300 may includeat least one selected from the group consisting of: carbon black, acarbon nanotube, and chromium oxide (CrO₂). In addition, the lightblocking layer 300 may include a resin or the like mixed with theaforementioned materials. Alternatively, the light blocking layer 300may be a black tape. The materials forming the light blocking layer 300is not limited to the above materials, and any known material capable ofblocking light may be applied.

The cushion layer 400 may be disposed on the light blocking layer 300.The cushion layer 400 serves to protect the display panel 100 from anexternal impact. The cushion layer 400 may be attached by an adhesive, adouble-sided tape or the like.

The cushion layer 400 may include a material having excellentcompressive stress and excellent shock and vibration absorbency. Thecushion layer 400 may include an acrylic resin, polyurethane, latex orthe like, but exemplary embodiments are not limited thereto.

The metal plate 500 may be disposed on the cushion layer 400. The metalplate 500 may have a substantially same shape as that of the displaypanel 100 in a plan view, and may be arranged to substantially overlapthe display panel 100.

FIG. 3 is a perspective view illustrating the metal plate according toan exemplary embodiment, FIG. 4 is a partial enlarged view illustratingarea “A” of FIG. 3, and FIG. 5 is a cross-sectional view illustrating anexemplary embodiment of the flexible display device in a folded state.

Referring to FIGS. 3, 4 and 5, the metal plate 500 according to anexemplary embodiment protects the display panel 100 from external heatand electromagnetic waves.

The metal plate 500 may include a bending portion 501 that may be bentwith respect to a folding line FL and planar portions 502 disposed onopposite sides of the bending portion 501. The bending portion 501 ofthe metal plate 500 may be arranged so as to substantially overlap thebending portion 101 of the display panel 100 in a plan view, andsimilarly, the planar portions 502 of the metal plate 500 may bearranged so as to substantially overlap the planar portions 102 of thedisplay panel 100 in a plan view.

The metal plate 500 may include a high modulus material. For example,the metal plate 500 may include at least one selected from the groupconsisting of invar, nobinite, stainless steel, and alloys thereof.

As described above, since including a high modulus material, the metalplate 500 of the flexible display device according to an exemplaryembodiment may not be deformed although a bending action of the displaypanel 100 is repeatedly performed.

In addition, the metal plate 500 according to an exemplary embodimentmay have a plurality of holes 500 h formed in a zigzag pattern withrespect to the folding line FL. That is, in the case where the metalplate 500 is folded with respect to the folding line FL, there is nooverlapping area among the plurality of holes 500 h. As such, since theplurality of holes 500 h are formed in a zigzag pattern with respect tothe folding line FL, the compression or tensile stress generated whenthe metal plate 500 is bent may be easily distributed.

Further, the hole 500 h according to an exemplary embodiment may have asubstantially elliptic shape in a plan view, and a major axis AL whichpasses through a center of the hole 500 h in a direction of major axisof the hole 500 h may be substantially parallel to the folding line FL.

As the hole 500 h has the above-described shape, that is, absent acorner, the compression or tensile stress that may be generated when themetal plate 500 is bent may be prevented from being concentrated on thecorner. In addition, as the major axis AL of the hole 500 h having theelliptical shape is arranged in parallel with the folding line FL, thecompression or tensile stress generated around the hole 500 h may besubstantially minimized.

The size and number of the holes 500 h may be altered according to thesize of the flexible display device and physical properties ofrespective layers constituting the flexible display device.

In addition, the hole 500 h according to an exemplary embodiment may bespaced apart from the folding line FL by a predetermined distance d.That is, a stress generated when the metal plate 500 is bent withrespect to the folding line FL becomes substantially maximum at an areaapart from the folding line FL by a predetermined distance d, not at anarea where the folding line FL is located.

The area where the stress is substantially maximum may vary depending onthe size of the flexible display device and the physical properties ofthe respective layers constituting the flexible display device. Ingeneral, however, the area where the stress is substantially maximum maycorrespond to a boundary line between the bending portion 501 and theplanar portion 502. Accordingly, the hole 500 h according to anexemplary embodiment may be formed at a boundary between the bendingportion 501 and the planar portion 502. However, exemplary embodimentsare not limited thereto, and the hole 500 h may be formed at an edgeportion of the planar portion 502 adjacent to the bending portion 501,or may be formed in the bending portion 501. That is, the hole 500 haccording to an exemplary embodiment may be formed in a region having aseparation distance from the folding line FL of d which is greater thanor equal to about 0.1 mm and less than or equal to about 10 mm.

That is, the hole 500 h according to an exemplary embodiment is formedat an area where the stress is substantially maximum so that thecompression or tensile stress generated when the metal plate 500 is bentmay be easily distributed.

FIGS. 6 and 7 are plan views illustrating a portion of a metal plateaccording to an alternative exemplary embodiment. The descriptions ofthe metal plate according to an exemplary embodiment will be omittedfrom the descriptions of the metal plate according to an alternativeexemplary embodiment.

Referring to FIGS. 6 and 7, the metal plate 500 according to analternative exemplary embodiment includes a bending portion 501 that maybe bent with respect to a folding line FL, and planar portions 501disposed on opposite sides of the bending portion 501. The bendingportion 501 of the metal plate 500 may be arranged so as tosubstantially overlap a bending portion 101 of a display panel 100 in aplan view, and similarly, the planar portions 502 of the metal plate 500may be arranged so as to substantially overlap planar portions 102 ofthe display panel 100 in a plan view.

The metal plate 500 according to an alternative exemplary embodiment mayhave a plurality of holes 500 h arranged in a zigzag pattern withrespect to the folding line FL. That is, in the case where the metalplate 500 is folded with respect to the folding line FL, there is nooverlapping area among the plurality of holes 500 h. Further, asillustrated in FIG. 6, the plurality of holes 500 h may be formed inpairs. In FIG. 6, each pair is depicted as including two holes 500 hspaced apart a predetermined distance, but exemplary embodiments are notlimited thereto. In one embodiment, the plurality of holes 500 h may bedefined in groups, each including two or more holes 500 h.

In addition, as illustrated in FIG. 7, said pairs of holes 500 h may bedefined in a zigzag pattern with respect to an imaginary line VLparallel to the folding line FL.

As such, as the plurality of holes 500 h are defined in a zigzag patternwith respect to the folding line FL, the compression or tensile stressgenerated when the metal plate 500 is bent may be easily distributed.

FIG. 8 is a partial enlarged view illustrating a portion of a displaypanel according to an exemplary embodiment, and FIG. 9 is across-sectional view taken along line I-I′ of FIG. 8.

Referring to FIGS. 8 and 9, the display panel 100 according to anexemplary embodiment includes a plurality of pixels including aswitching thin film transistor (“TFT”) 10, a driving TFT 20, a capacitor80, and an OLED 210. The OLED 210 may be suitable to be applied to aflexible display device in that the OLED 210 may be formed thin andlight, and the like. As used herein, the term “pixel” refers to asmallest unit for displaying an image, and the display panel 100displays an image using a plurality of pixels.

Further, although each pixel is depicted in the drawings as includingtwo TFTs and one capacitor, exemplary embodiments are not limitedthereto. Each pixel may include three or more TFTs and two or morecapacitors and may further include additional wirings into variousstructures.

The display panel 100 includes a substrate 110, a gate line 151 on thesubstrate 110, a data line 171 and a common power line 172 insulatedfrom and intersecting the gate line 151. In general, each pixel may bedefined by the gate line 151, the data line 171, and the common powerline 172 as a boundary, but exemplary embodiments are not limitedthereto. The pixels may be defined by a pixel defining layer or a blackmatrix.

The substrate 110 may include a flexible material. An example of theflexible material may include a plastic material. For example, thesubstrate 110 may include one selected from the group consisting of:kapton, polyethersulphone (PES), polycarbonate (PC), polyimide (PI),polyethyleneterephthalate (PET), polyethylene naphthalate (PEN),polyacrylate (PAR), fiber reinforced plastic (FRP), and the like.

Further, the substrate 110 may have a thickness ranging from about 5 μmto about 200 μm. In the case where the substrate 110 has a thickness ofless than about 5 μm, it is difficult for the substrate 110 to stablysupport the OLED 210. On the other hand, in the case where the substrate110 has a thickness of about 200 μm or more, the flexiblecharacteristics of the substrate 110 may be degraded.

A buffer layer 120 is disposed on the substrate 110. The buffer layer120 is configured to prevent permeation of undesirable elements into theTFT 20 and to planarize a surface therebelow, and may include suitablematerials for preventing permeation and/or planarizing. For example, thebuffer layer 120 may include one of the followings: a silicon nitride(SiN_(x)) layer, a silicon oxide (SiO₂) layer, and a silicon oxynitride(SiO_(x)N_(y)) layer. However, the buffer layer 120 is not invariablynecessary and may be omitted based on the kinds of the substrate 110 andprocess conditions thereof.

A switching semiconductor layer 131 and a driving semiconductor layer132 are disposed on the buffer layer 120. The switching semiconductorlayer 131 and the driving semiconductor layer 132 may include at leastone of the followings: a polycrystalline silicon layer, an amorphoussilicon layer, and an oxide semiconductor including, for example, indiumgallium zinc oxide (IGZO) and indium zinc tin oxide (IZTO). For example,in the case where the driving semiconductor layer 132 includes apolycrystalline silicon layer, the driving semiconductor layer 132includes a channel area that is not doped with impurities and p+ dopedsource and drain areas that are formed on opposite sides of the channelarea. In such an exemplary embodiment, p-type impurities, such as boronB, may be used as dopant ions and B₂H₆ is typically used. Suchimpurities may vary depending on the kinds of TFTs. The driving TFT 20according to an exemplary embodiment uses a p-channel metal oxidesemiconductor (PMOS) TFT including p-type impurities, but exemplaryembodiments are not limited thereto. Alternatively, the driving TFT 20may use an n-channel metal oxide semiconductor (NMOS) TFT or acomplementary metal oxide semiconductor (CMOS) TFT.

A gate insulating layer 140 is disposed on the switching semiconductorlayer 131 and the driving semiconductor layer 132. The gate insulatinglayer 140 may include at least one of: insulating layer formed usingtetraethylorthosilicate (TEOS), silicon nitride (SiN_(x)), and siliconoxide (SiO₂). For example, the gate insulating layer 140 may have adouble-layer structure where a SiN_(x) layer having a thickness of about40 nm and a TEOS insulating layer, for example, TEOS oxide, having athickness of about 80 nm are sequentially stacked.

A gate wiring including gate electrodes 152 and 155 is disposed on thegate insulating layer 140. The gate wiring further includes the gateline 151, a first capacitor plate 158, and other lines. In addition, thegate electrodes 152 and 155 are disposed to overlap at least a portionof the semiconductor layers 131 and 132, for example, a channel areathereof. The gate electrodes 152 and 155 serve to substantially preventthe channel area from being doped with impurities when source and drainareas of the semiconductor layers 131 and 132 are doped with impuritiesduring the process of forming the semiconductor layers 131 and 132.

The gate electrodes 152 and 155 and the first capacitor plate 158 aredisposed on a substantially same layer and include a substantially samemetal material. The gate electrodes 152 and 155 and the first capacitorplate 158 may include at least one of molybdenum (Mo), chromium (Cr),and tungsten (W).

An insulating interlayer 160 overlapping the gate electrodes 152 and 155is disposed on the gate insulating layer 140. The insulating interlayer160, similar to the gate insulating layer 140, may include or be formedof silicon nitride (SiNx), silicon oxide (SiOx), insulating layer formedusing tetraethylorthosilicate (TEOS) or the like, but exemplaryembodiments are not limited thereto.

A data wiring including source electrodes 173 and 176 and drainelectrodes 174 and 177 is disposed on the insulating interlayer 160. Thedata wiring further includes the data line 171, the common power line172, a second capacitor plate 178, and other lines. In addition, thesource electrodes 173 and 176 and the drain electrodes 174 and 177 areconnected to a source area and a drain area of the semiconductor layers131 and 132, respectively, through a contact hole defined in the gateinsulating layer 140 and the insulating interlayer 160.

As such, the switching TFT 10 includes the switching semiconductor layer131, the switching gate electrode 152, the switching source electrode173, and the switching drain electrode 174, and the driving TFT 20includes the driving semiconductor layer 132, the driving gate electrode155, the driving source electrode 176, and the driving drain electrode177. Configurations of the TFTs 10 and 20 are not limited to the aboveembodiments, and thus may be modified into various structures that areknown to and may be easily conceived by those skilled in the pertinentart.

In addition, the capacitor 80 includes the first capacitor plate 158 andthe second capacitor plate 178. The insulating interlayer 160 isinterposed between the first capacitor plate 158 and the secondcapacitor plate 178.

The switching TFT 10 may function as a switching element configured toselect pixels to perform light emission. The switching gate electrode152 is connected to the gate line 151. The switching source electrode173 is connected to the data line 171. The switching drain electrode 174is spaced apart from the switching source electrode 173 and is connectedto the first capacitor plate 158.

The driving TFT 20 applies, to a pixel electrode 211, a driving powerwhich allows a light emitting layer 212 of the OLED 210 in the selectedpixel to emit light. The driving gate electrode 155 is connected to thefirst capacitor plate 158. The driving source electrode 176 and thesecond capacitor plate 178 each are connected to the common power line172. The driving drain electrode 177 is connected to the pixel electrode211 of the OLED 210 through a contact hole.

With the aforementioned structure, the switching TFT 10 is driven by agate voltage applied to the gate line 151 and serves to transmit a datavoltage applied to the data line 171 to the driving TFT 20. A voltageequivalent to a difference between a common voltage applied to thedriving TFT 20 from the common power line 172 and the data voltagetransmitted from the switching TFT 10 is stored in the capacitor 80, anda current corresponding to the voltage stored in the capacitor 80 flowsto the OLED 210 through the driving TFT 20, such that the OLED 210 mayemit light.

A planarization layer 165 is disposed to cover the data wiring, e.g.,the data line 171, the common power line 172, the source electrodes 173and 176, the drain electrodes 174 and 177, and the second capacitorplate 178, which are patterned into a substantially same layer on theinsulating interlayer 160.

The planarization layer 165 serves to substantially eliminate a stepdifference and planarize a surface so as to increase luminanceefficiency of the OLED 210 to be formed thereon. The planarization layer165 may include at least one of the following materials: a polyacrylateresin, an epoxy resin, a phenolic resin, a polyamide resin, a polyimideresin, an unsaturated polyester resin, a polyphenylen ether resin, apolyphenylene sulfide resin, and benzocyclobutene (BCB).

The pixel electrode 211 of the OLED 210 is disposed on the planarizationlayer 165. The pixel electrode 211 is connected to the drain electrode177 through a contact hole defined in the planarization layer 165.

A pixel defining layer 190 exposing at least a portion of the pixelelectrode 211 to define a pixel area is disposed on the planarizationlayer 165. The pixel defining layer 190 may include a resin such as apolyacrylate resin and a polyimide resin.

In the pixel area, the light emitting layer 212 is disposed on the pixelelectrode 211 and a common electrode 213 is disposed on the pixeldefining layer 190 and the light emitting layer 212. The light emittinglayer 212 includes a low molecular organic material or a high molecularorganic material. At least one of a hole injection layer HIL and a holetransporting layer HTL may further be disposed between the pixelelectrode 211 and the light emitting layer 212, and at least one of anelectron transporting layer ETL and an electron injection layer EIL mayfurther be disposed between the light emitting layer 212 and the commonelectrode 213.

The pixel electrode 211 and the common electrode 213 may be formed asone of a transmissive electrode, a transflective electrode, and areflective electrode.

Transparent conductive oxide (“TCO”) may be used to form a transmissiveelectrode. Such TCO may include at least one selected from the groupconsisting of: indium tin oxide (ITO), indium zinc oxide (IZO), zincoxide (ZnO), or indium oxide (In₂O₃)

A metal, e.g., magnesium (Mg), silver (Ag), gold (Au), calcium (Ca),lithium (Li), chromium (Cr), aluminum (Al), and copper (Cu), or an alloythereof may be used to form a transflective electrode and a reflectiveelectrode. In such an exemplary embodiment, whether an electrode is atransflective type or a reflective type depends on the thickness of theelectrode. Typically, the transflective electrode has a thickness ofabout 200 nm or less and the reflective electrode has a thickness ofabout 300 nm or more. As the thickness of the transflective electrodedecreases, light transmittance and resistance increase. On the contrary,as the thickness of the transflective electrode increases, lighttransmittance decreases.

In addition, the transflective electrode and the reflective electrodemay have a multilayer structure which includes a metal layer including ametal or a metal alloy and a TCO layer stacked on the metal layer.

A thin film encapsulation layer 250 is disposed on the common electrode213. The thin film encapsulation layer 250 includes one or moreinorganic layers 251 and 253 and one organic layer 252. Further, thethin film encapsulation layer 250 may have a structure in which one ormore inorganic layers 251 and 253 and one organic layer 252 arealternately stacked. In such an exemplary embodiment, an inorganic layer251 is disposed at a lowermost portion. That is, the inorganic layer 251is disposed most adjacent to the OLED 210.

The thin film encapsulation layer 250 is depicted as including twoinorganic layers 251 and 253 and one organic layer 252 disposed betweenthe two inorganic layers 251 and 253, but exemplary embodiments are notlimited thereto.

The inorganic layers 251 and 253 may include one or more inorganicmaterials selected from the group consisting of: Al₂O₃, TiO₂, ZrO, SiNx,SiO₂, AlON, AN, SiON, Si₃N₄, ZnO, and Ta₂O₅. The inorganic layers 251and 253 may be formed through methods such as a chemical vapordeposition (CVD) method or an atomic layer deposition (ALD) method.However, exemplary embodiments are not limited thereto, and theinorganic layers 251 and 253 may be formed using various methods knownto those skilled in the art.

The organic layer 252 may include a polymer-based material. Examples ofthe polymer-based material may include, for example, an acrylic resin,an epoxy resin, polyimide, and polyethylene. In addition, the organiclayer 252 may be formed through a thermal deposition process. Inaddition, the thermal deposition process for forming the organic layer252 may be performed at a temperature range that may not damage the OLED210. However, exemplary embodiments are not limited thereto, and theorganic layer 252 may be formed using various methods known to thoseskilled in the pertinent art.

The inorganic layers 251 and 253 which have a high density of thin filmmay prevent or efficiently reduce permeation of, mostly, moisture oroxygen. Permeation of moisture and oxygen into the OLED 210 may belargely prevented by the inorganic layers 251 and 253.

The thin film encapsulation layer 250 may have a thickness of about 10μm or less. Accordingly, the OLED display panel 100 may also have asignificantly small thickness. By applying the thin film encapsulationlayer 250 in such a manner, the OLED display panel 100 may have flexiblecharacteristics.

As set forth hereinabove, in the flexible display device according toone or more exemplary embodiments, the metal plate for dissipating heatand shielding electromagnetic waves includes a high modulus material,such that deformation of the metal plate may be substantially preventedalthough a bending action is repeatedly performed.

In addition, by forming a predetermined pattern at the bending portionof the high modulus metal plate, the stress of the metal plate may beeasily distributed.

While the present inventive concept has been illustrated and describedwith reference to the exemplary embodiments thereof, it will be apparentto those of ordinary skill in the art that various changes in form anddetail may be made thereto without departing from the spirit and scopeof the present inventive concept.

What is claimed is:
 1. A flexible display device comprising: a displaypanel capable of being bent with respect to a folding line; and a metalplate disposed on the display panel and capable of being bent withrespect to the folding line, wherein the metal plate has a plurality ofholes disposed on each side of the folding line to substantially overlapthe display panel, and 1 the plurality of holes comprises: a firstplurality of holes disposed on one side of the folding line and spacedapart from the folding line at a first distance; and a second pluralityof holes disposed on the other side of the folding line and spaced apartfrom the folding line at the first distance, and each of the firstplurality of holes does not overlap any of the second plurality of holeswhen folded with respect to the folding line.
 2. The flexible displaydevice as claimed in claim 1, wherein each of the plurality of holes hasan elliptical shape in a plan view.
 3. The flexible display device asclaimed in claim 2, wherein the elliptical shape has a major axisparallel to the folding line.
 4. The flexible display device as claimedin claim 1, wherein the metal plate comprises: a bending portion bentwith respect to the folding line; and a planar portion extending fromthe bending portion.
 5. The flexible display device as claimed in claim4, wherein each of the plurality of holes is formed at a boundarybetween the bending portion and the planar portion.
 6. The flexibledisplay device as claimed in claim 1, wherein the plurality of holes arespaced apart from the folding line.
 7. The flexible display device asclaimed in claim 1, wherein the plurality of holes are spaced apart fromthe folding line by a distance greater than or equal to about 0.1 mm andless than or equal to about 10 mm.
 8. The flexible display device asclaimed in claim 1, wherein the plurality of holes comprise at least onegroup of holes disposed on one side of the folding line, each group ofholes comprising a predetermined number of holes.
 9. The flexibledisplay device as claimed in claim 8, wherein the groups of holes areformed in a zigzag pattern with respect to an imaginary line parallel tothe folding line.
 10. The flexible display device as claimed in claim 1,wherein the metal plate comprises a high modulus material.
 11. Theflexible display device as claimed in claim 1, wherein the metal platecomprises at least one selected from the group consisting of: copper(Cu), invar, nobinite, stainless steel, and alloys thereof.
 12. Theflexible display device as claimed in claim 1, wherein the metal platehas a substantially same shape as a shape of the display panel in a planview.
 13. The flexible display device as claimed in claim 1, furthercomprising a light blocking layer disposed between the display panel andthe metal plate.
 14. The flexible display device as claimed in claim 1,further comprising a cushion layer disposed between the display paneland the metal plate.
 15. A flexible display device comprising: a metalplate capable of being bent with respect to a folding line; a displaypanel disposed on the metal plate and capable of being bent with respectto the folding line; and a touch sensor disposed on the display panel,wherein the metal plate has a plurality of holes disposed on each sideof the folding line to substantially overlap the display panel, and theplurality of holes comprises: a first plurality of holes disposed on oneside of the folding line and spaced apart from the folding line at afirst distance; and a second plurality of holes disposed on the otherside of the folding line and spaced apart from the folding line at thefirst distance, and each of the first plurality of holes does notoverlap any of the second plurality of holes when folded with respect tothe folding line.
 16. The flexible display device as claimed in claim15, further comprising a polarizer disposed on the display panel. 17.The flexible display device as claimed in claim 15, wherein each of theplurality of holes has an elliptical shape in a plan view.
 18. Theflexible display device as claimed in claim 15, wherein the ellipticalshape has a major axis parallel to the folding line.
 19. The flexibledisplay device as claimed in claim 15, wherein the plurality of holescomprise at least one group of holes disposed on one side of the foldingline, each group of holes comprising a predetermined number of holes.20. The flexible display device as claimed in claim 19, wherein thegroups of holes are formed in a zigzag pattern with respect to animaginary line parallel to the folding line.